Sun Bear

ABOUT

Small but mighty: The sun bear is the smallest of the world's eight bear species, about half the size of the American black bear. Its common name comes from the white or yellowish crescent marking on its chest, which many people think looks like the rising or setting sun. Each bear’s crest is individual—like fingerprints.

The sun bear’s jaws provide a powerful bite force and are often used to tear into trees to get at the burrowing insects beneath the bark. They have a distinctive pigeon-toed walk, an adaptation to their arboreal lifestyle. Like other bears, sun bears have an incredible sense of smell, thought to be several thousand times better than that of humans.

HABITAT AND DIET

Tree, sweet tree: In the Malay language, the sun bear is called basindo nan tenggil, which means “he who likes to sit high.” It certainly lives up to that reputation! The sun bear likes to make its home in the branches of trees. Its small size, 4-inch-long (10 centimeters) claws, and large paws with hairless soles help the little bear move about with ease high up in trees.

Those branches also make a nice place to build a nest for resting or sunbathing during the day, although in areas undisturbed by humans, sun bears are more likely to rest on the ground. Their eyes are more forward-facing than those of longer-snouted bears like polar bears, which is another adaptation thought to aid in climbing.

The sun bear has all the tools necessary to protect itself. Those claws and canine teeth are handy weapons in a fight. If a predator were to latch on during a struggle, the sun bear can turn in its loose skin and bite its attacker. And even though the sun bear lives in a hot, humid climate, its short, sleek, dark-brown coat is unusually thick and dense to protect the animal against twigs, branches, falls, and heavy rain. What’s more, the sun bear can be a quick mover when it needs to be, outpacing more lumbering bears like giant pandas.

The omnivorous sun bear relies primarily on fruit and insects to meet its needs. Its front paws and long claws rip open trees in search of insects or sap. Other occasional food choices include small birds, fruit, honey, lizards, rodents, and soft parts of palm trees. Strong jaws and teeth even help this bear open coconuts!

The sun bear’s especially long tongue is perfectly suited for getting at honey and insects inside trees and other tight places. Its appetite for coconuts, oil palms, and other commercial crops has led to a lot of conflict between sun bears and humans. Sadly, this conflict is a significant conservation threat to the sun bear, as the little bears are often killed or confiscated for the pet trade.

At the San Diego Zoo, the sun bears eat fruits, vegetables, and an omnivore pellet that’s a lot like dog kibble. They also receive bones to gnaw on twice a week and, for enrichment, an assortment of goodies like mealworms, crickets, and even peanut butter!

FAMILY LIFE

Cub scouting: Sun bears don’t have a particular breeding season; in fact, adult female sun bears are the only bear species known to cycle several times each year. Nests have been observed in leafy vegetation on the ground or in hollow logs. Cubs are born hairless and helpless, unable to hear or smell, and are completely dependent upon their mother for food, warmth, and protection. Mothers sometimes walk upright and carry their babies in their paws or mouth to move them from place to place.

Sun bear youngsters are able to run and play at about 4 to 5 months of age, and they are probably naturally weaned at about 18 months of age. They probably stay with their mother, however, for about two years as they learn the facts of life.

Sun bears vocalize using a variety of different sounds. Adult bears use a clucking noise, resembling the sound of a hen, which is a typical contact call signaling friendly intent. Aggressive sun bears can bark, growl, and roar, not unlike other bears. Cubs hum while nursing and squawk or cry when in need of their mother’s attention.

The degree to which sun bears use chemical communication has not been well documented. Sun bears do rub against rocks and trees, a behavior known from other bear species to deposit hair and other scent samples that others can investigate. Sun bears do sniff the urine and feces of other sun bears and appear to get some chemical information from these “messages.” However, sun bears are not known to engage in anogenital scent marking like their distant relative, the giant panda.

AT THE ZOO

Our very first sun bear arrived in 1928, and it was quite an accomplishment for a young zoo in a small city to obtain such a rare bear! In 1935, two more arrived. On New Year’s Eve, 1938, we welcomed our first Malayan sun bear cub; sadly, it did not survive long. However, more cubs were born in the early 1940s. It was a challenge to keep up with these clever bears; a 1940 article from our member magazine, ZOONOOZ, recalls:

“We gave them a cement tree, which they proceeded to break to pieces with teeth and claws. Before the first week was over they had all of the cement broken off the tree and the branches, made of strong rods of reinforcement iron, bent all out of shape, and the metal lath upon which the cement gunnite had been shot hanging in shreds. Finally we took them out and built a tree with reinforced pipes for limbs and the heaviest, hardest cement possible to obtain sprayed on very, very thick. They put this tree through every test, but it has stood and how they love to go up and down it."

In 1965, a Malayan sun bear named Boo Boo was honorably “discharged” from the United States Navy and donated to the Zoo’s Children’s Zoo after serving more than six months as the mascot to the Seabees of MCB Ten in the fighting zone of Vietnam. Boo Boo held the distinction of being one of the few animals to receive dental care from a navy dentist; apparently, the Seabees fed her a lot of sweets, causing dental problems. Another “celebrity” sun bear at that time was Josephine, who had been the mascot of the University of California, Los Angeles’ football team in 1961.

When Sun Bear Forest opened at the Zoo in 1989, five young Malayan sun bears quickly, and true to form, tore up their new home, ripping out grass, trees, and anything else they could find. Zoo architects and horticulturists again had to redesign the exhibit to make it more "bear proof." Still, the new exhibit was a success, as we welcomed the birth of Stanley later that year.

Our Zoo is currently home to two Bornean sun bears, Marcella and Francis. As the only successfully reproducing female Bornean sun bear in the U.S., Marcella is a great ambassador for sun bear conservation. Her first cub, Danum, was born in 2004, the first Bornean sun bear to be born in North America. Second son Bulan was born in 2006, and in 2008, Marcella had twins Pagi and Palu. Because sun bears are so hard to find in the wild, Marcella and her babies allowed researchers and keepers the rare chance to study mother/cub interactions. All four of Marcella’s offspring have moved to other zoos as part of the Species Survival Plan for sun bears.

CONSERVATION

Sun bears are a species vulnerable to extinction. It is unknown how many are left in the wild, since their secretive nature makes them hard to find, and few studies have focused on these animals. This lack of data currently prevents them from being listed as endangered; however, wild sun bear populations are believed to be dwindling rapidly, due mainly to habitat loss from farming and logging, poaching (both for meat and use in medicines), and even the pet trade. Their appetite for oil palm and other commercial crops has led to a lot of trouble between sun bears and humans, and wild sun bears are walking a survival tightrope.

The population of this rare bear is thought to have declined more than 30 percent in the last 30 years. Although it is illegal to kill sun bears, laws protecting them are rarely enforced.

San Diego Zoo Global, through past participation in the Bornean Sun Bear Species Survival Plan and current efforts with zoos worldwide, is certainly doing its part to help these petite and fun-loving bears. We also collaborate with the Bornean Sun Bear Conservation Centre (BSBCC) in Sabah, Borneo. BSBCC serves as a rescue and rehabilitation facility for orphaned and injured sun bears.

We are excited about developing our partnership into a research opportunity that will aid in the conservation of the smallest bear on Earth and could lend insight into this bear’s biology. We know from our past work, for example, that sun bear mothers and panda mothers are very similar in their attentive maternal-care styles, and both pandas and sun bears differ from the less active hibernating bears like brown and black bears. What other similarities and differences between the bear species will we find?